I just built a new computer, but swapped out my network card from my old computer to put into my PC. For some reason I'm experiencing some issues with the internet and overall speeds.
Originally I was connected through a router to my modem; my ISP offers 5MB-6MB download. I noticed a download was at about 30 kb/s so I started looking into the problem. I ran a speed test and was at 114ms latency and 0.95 mb/s download. I reset my router and was at 4 mb/s download and 15 latency, but within a few seconds it jumped back to where it was.
I called my ISP and they had me connect it directly to the modem. At first I accidentally connected the wrong Ethernet cable, so it was my modem directly to a different PC, and they had said the latency was fixed. When I fixed it though to the Ethernet cable that goes to my new PC, the latency jumped back up close to 100.
Because of this, I don't think it's the router, and because it was working with the other accidental connection, I don't think it's the modem. I think it's either something with my PC, or my Ethernet cables. I have a little splitter thing connecting two ethernet cables to get connection to my PC because of how far away it's located from my modem/router, but I used that on the PC before I built my new one without any problems.
I also tried plugging the cable into the onboard network port but it didn't even read it or connected to the internet.
I've also updated the drivers on my network card as well as updated my firmware on my router (though like I said, don't think that's it.)
Can you elaborate on what you mean by splitter? Is it a switch or a hub? Also, just to be clear - when you hooked your other PC to the modem, the lag problem went away?
One thing is to check the duplex settings on your LAN card. (right-click -> properties -> Configure -> Link Speed \ Advanced Tab) If it is set to a static number like 10Mbps, try setting it to "auto" and see if that helps.
Other things to try are swapping the cable, removing the "splitter" from the situation, and shortening the distance between the modem/PC (although you should be fine unless you're exceeding 100 meters or running next to some kind of interference)